1. Field of the Invention
The present invention relates to a method and apparatus for assisting design using a computer, more particularly relates to a method and apparatus for assisting the design of the individual parts of a product comprised of a large number of parts, such as an automobile.
2. Description of the Related Art
When making something, especially when making something by mass production, basically one draws up a design, fabricates a prototype based on that design, assesses if the prototype satisfies the required performances, feeds back the results to the design, modifies the design to overcome any problems, makes another prototype, and reassesses the same. This is repeated until the required performances are satisfied, then full-scale production is started using the design as the specifications satisfying the required performances.
Greater efficiency is being sought in these processes. For example, computer-aided design (CAD) is being introduced in the work of preparing the design drawings and computer simulation is being used to replace the steps of making the prototypes and assessment.
Whatever the case, a "good design" may be said to be a design which satisfies the required performances without repeated design modifications or with as little modifications as possible.
In particular, in the case where a product is comprised of a large number of parts and these have an effect on each other, it is necessary that the individual parts satisfy the basic performances as unit parts and that the product satisfy the overall performances of the product. There is therefore a high probability of repeated design modifications. To make a good design, it is particularly necessary therefore to efficiently design the product with due consideration to both the parts and product.
For a good design, it is necessary to store the valuable knowledge obtained through past experience and make effective use of the same.
However, this valuable knowledge is usually stored in the minds of individuals. There will therefore often be waste in the same design division with the same mistakes repeated and the same thing having to be redone.
Therefore, various attempts have been made to construct a system for storing knowledge using a computer and making use of the stored knowledge in accordance with need so as thereby to enable all designers to use the stored knowledge and therefore improve the efficiency of the design division as a whole.
Recently, design assisting apparatuses using so-called "expert systems" for using artificial intelligence (AI), comprised of a knowledge base storing expert knowledge and a reasoning mechanism, and applying the knowledge and performing reasoning in accordance with a problem have been developed in numerous fields.
For example, several design assisting apparatuses for the design work of automobiles have already been disclosed. For example, there are the design routine assisting apparatuses disclosed in Japanese Unexamined Patent Publication (Kokai) No. 2-126370, Japanese Unexamined Patent Publication (Kokai) No. 2-126371, and Japanese Unexamined Patent Publication (Kokai) No. 2-128278. In these apparatuses, a plurality of types of knowledge on routines required for a design are stored combined and arranged in a hierarchical structure.
Further, in the apparatus disclosed in Japanese Unexamined Patent Publication (Kokai) No. 5-81062, there are disclosed a step of checking the normality of the individual unit parts and a step of judging the normality of the product as a whole when combining these parts.
In constructing a design assisting system using a computer, however, the important thing is that the system be easy to use by the user, that is, the designer, and that not too much time be taken for the reasoning and judgement in the computer.
For this purpose, the system must match with the characteristics of the design work for the product to be designed.
Accordingly, when considering a design assisting system for automobile parts, it is necessary to examine the characteristics of the design work for auto parts.
When taking the example of auto parts and considering the characteristics of their design work, the first thing which should be noted is that automobiles are comprised of an extremely large number of parts and that these are all complicatedly related with each other.
When considering the design of individual parts, however, in so far as the individual parts are objects with self-complete shapes, what are affected are certain characteristics of other parts and what give an effect are certain characteristics of those parts, i.e., there is no mutual effect with all the parameters of other parts.
If one can determine the types and characteristics of other parts which are affected, the types and characteristics of other parts which give an effect, and what items of the final product are affected, then one can proceed independently with the design of the different parts. If not, then unless the detailed specifications of a large component, for example, an engine, having an effect on a large number of other parts are all determined, no progress can be made in the design of the large number of parts affected by the engine.
That is, it is not necessary to consider the effects from elsewhere and the effects on other locations at all times in the detailed sections of the design work of parts.
In a design assisting system using a large data base where everything is connected together, knowledge not required for the design of a part will be considered and time will be wasted in the reasoning or the system will become hard to handle and in the end will tend to not be effectively utilized.
The apparatuses disclosed in Japanese Unexamined Patent Publication (Kokai) No. 2-126370, Japanese Unexamined Patent Publication (Kokai) No. 2-126371, and Japanese Unexamined Patent Publication (Kokai) No. 2-128278, however, are complicated ones using data bases storing the knowledge on the plurality of routines necessary for design combined and arranged in a hierarchical structure. Various improvements have been made to reduce this complexity, but from the way the basic data bases are constructed, there is a tendency for time to be taken in the reasoning and searching.
Further, even in the apparatus disclosed in Japanese Unexamined Patent Publication (Kokai) No. 5-81062, the same knowledge data base is used for judging the normality of the individual unit parts and the normality of the product as a whole, so when the amount of knowledge becomes huge, time is taken for searching. When parts designed with reference to knowledge covering the product as a whole as well are combined, a need arises for redesigning the parts when assembling the product.